1 00:00:03,180 --> 00:00:07,220 Now let's find out how to actually use this user command. 2 00:00:07,440 --> 00:00:12,300 Again since it's a file on the file system we know we can use the man subsystem to get some information 3 00:00:12,300 --> 00:00:14,430 and help on this particular command. 4 00:00:16,820 --> 00:00:22,500 Briefly the user Dell command deletes a user account and related files. 5 00:00:22,680 --> 00:00:26,430 We look forward here to the dash f option. 6 00:00:26,450 --> 00:00:32,060 It stands for force and it removes the account even if the user is logged in. 7 00:00:32,150 --> 00:00:34,420 And it also deletes the user's home directory. 8 00:00:34,460 --> 00:00:40,400 Even if that home directory is shared with another user normal user accounts don't share the same home 9 00:00:40,400 --> 00:00:42,390 directories usually or they shouldn't. 10 00:00:42,560 --> 00:00:47,690 But in some cases you might have multiple application accounts that share the same home directory. 11 00:00:47,690 --> 00:00:52,970 Here's a little note here that says to use caution when using this option. 12 00:00:53,230 --> 00:00:55,690 Now let's keep looking through the options here. 13 00:00:55,700 --> 00:01:01,640 The dash r option is the one that we're most interested in as it removes the user's home directory. 14 00:01:01,640 --> 00:01:03,830 So let's try out this user Dell command. 15 00:01:03,920 --> 00:01:10,640 First let's look at some users on our local system here will do tell at sea password and we can see 16 00:01:10,640 --> 00:01:17,570 we have Einstein Isaac t Edison J Locke et cetera and these are all accounts that were created through 17 00:01:17,570 --> 00:01:23,200 previous exercises and through some of my previous work I've been doing on this virtual machine. 18 00:01:23,270 --> 00:01:30,610 So if we do this let's delete the Einstein user pseudo user Del Einstein and hit enter. 19 00:01:30,980 --> 00:01:37,400 Now if we run ID against the Einstein user it will say hey there is no Einstein user available. 20 00:01:37,460 --> 00:01:40,390 So sure enough the user DEL command got rid of Einstein. 21 00:01:40,560 --> 00:01:42,860 And let's look in the home directory. 22 00:01:42,860 --> 00:01:48,110 So this really prove to us that running user Dell without any options removes the user but leaves their 23 00:01:48,110 --> 00:01:54,080 files because you can see here the Einstein directory is still listed in for home. 24 00:01:54,290 --> 00:01:59,960 This might come in handy if you want access to a user's files after they have been removed. 25 00:01:59,960 --> 00:02:01,430 Now there's something else to notice here. 26 00:02:01,430 --> 00:02:06,940 Notice that the user and group for the Einsteins home directory are actually numbers. 27 00:02:06,950 --> 00:02:13,320 This is because there is no account associated with UAD 1001 any longer because we deleted that account. 28 00:02:13,490 --> 00:02:17,540 They had the ID of 1001 which is the Einstein account. 29 00:02:17,540 --> 00:02:23,600 So if you ever run an ls command and see numbers where you would normally see a user then know that 30 00:02:23,600 --> 00:02:30,680 you're looking at a UI ID Orji ID and that there is no account associated with that particular ID or 31 00:02:30,920 --> 00:02:31,930 ID. 32 00:02:31,940 --> 00:02:36,200 So while we're talking about you IDs let's look at a couple of users. 33 00:02:36,230 --> 00:02:39,190 The root user always has the idea of zero. 34 00:02:39,190 --> 00:02:45,440 So if we do ideaspace DSU which returns a user id follow that with the root account we should always 35 00:02:45,440 --> 00:02:47,040 get back zero. 36 00:02:47,060 --> 00:02:52,010 Now there are some other accounts on the system that are considered to be system accounts or application 37 00:02:52,010 --> 00:02:52,850 accounts. 38 00:02:52,850 --> 00:02:55,010 Let's look at another one of those. 39 00:02:55,010 --> 00:02:58,210 Let's look at the as each account here. 40 00:02:58,340 --> 00:03:02,240 It has an ID or user id of 74. 41 00:03:02,240 --> 00:03:06,030 Now let's look at the ID for our current vagrant user. 42 00:03:06,290 --> 00:03:08,120 It has a new idea of 1000. 43 00:03:08,270 --> 00:03:11,600 As you saw earlier Einstein has a new idea of 1001. 44 00:03:11,690 --> 00:03:17,290 So I don't know if you notice a pattern here but really system accounts have lower you IDs. 45 00:03:17,300 --> 00:03:22,610 This is actually set in a file called log in daat deaths and that's located in SC. 46 00:03:22,610 --> 00:03:24,630 So let's just look at that really quickly. 47 00:03:28,970 --> 00:03:31,760 A page down here until we get here. 48 00:03:31,940 --> 00:03:34,520 Here we see you I.D. men you I.D. man. 49 00:03:34,530 --> 00:03:39,840 So these are the minimum and maximum values for automatic selection and user add. 50 00:03:39,900 --> 00:03:46,170 So when you create the very first user on a Linux system it's going to have a user id of 1000. 51 00:03:46,170 --> 00:03:50,610 And by the way that is the user id of our bigger user because that was the first account created on 52 00:03:50,610 --> 00:03:51,480 the system. 53 00:03:51,540 --> 00:03:55,230 Then the next time we enter an account the number will get incremented by 1. 54 00:03:55,230 --> 00:03:59,940 So Einstein was the next account that was created so it had a new idea of 1001 so on. 55 00:04:00,210 --> 00:04:05,260 By the way if you look below this you see sis you I.D. men and you ID Max. 56 00:04:05,280 --> 00:04:11,550 This means that the maximum user ID for a system account or what's considered a system account is nine 57 00:04:11,550 --> 00:04:16,810 hundred and ninety nine if you want to make sure that you're not deleting a very important account. 58 00:04:16,920 --> 00:04:23,940 Perhaps it's a good idea to check your ID first if it's less than 1000 then clearly be careful of what 59 00:04:23,940 --> 00:04:28,190 you're doing because it could operate a service that you may need on your server. 60 00:04:28,500 --> 00:04:34,830 Ok let's jump out of here and let's move on to our next user id dash you Isaac. 61 00:04:34,980 --> 00:04:41,300 This user has a new idea of 1002 let's delete this user but this time remove its home directory. 62 00:04:44,670 --> 00:04:45,100 All right. 63 00:04:45,100 --> 00:04:50,720 If we try to get the user id of the user again it says now it's deleted it's gone there is no such user. 64 00:04:50,950 --> 00:04:56,340 And if we look for a home directory for this user it doesn't exist. 65 00:04:56,350 --> 00:05:01,690 So again that proves the dash or option removes the home directory and all the files that were within 66 00:05:01,750 --> 00:05:03,280 that home directory as well.